All about Remote Authentication Dial-In User Service (RADIUS)

In order to provide centralized authentication, authorization, and accounting (AAA) management services for local network resources like routers and switches, RADIUS, which stands for Remote Authentication Dial-In User Service, was created back in the 1990s.

 

But since the protocol has shown to be so adaptable, cloud providers are experimenting with ways RADIUS can be used to support Zero Trust Network Access (ZTNA) and reduce the risks connected with over-the-air attacks on wireless networks and Virtual private networks (VPNs).

 

Anyone in charge of administering a network must have a solid grasp of RADIUS since it is an integral component of many network security solutions. Since RADIUS is a standards-based protocol, an IETF specification serves as its definition.

 

A request is sent by the RADIUS client to the RADIUS server whenever an end user wants to connect to it. Once the end user's credentials have been verified by the RADIUS server, the end user will be given the authorization to connect to the RADIUS client. A RADIUS client can be any networking device used to authenticate users at the application layer.

 

The transport protocol used by RADIUS is UDP. 

 

The UDP protocol is connectionless, which means that each packet is sent on its own and without the need for a connection to be made first. Because it can accommodate a high number of clients without using a lot of server resources, this makes RADIUS particularly scalable. RADIUS makes use of error correction to make sure packets are delivered properly.

 

As it transfers the expense of acquiring and maintaining RADIUS server infrastructure to a third-party cloud provider, the cloud delivery model for RADIUS can lower an organization's capital expenditures (CapEx).

 

What is Remote Authentication Dial-In User Service (RADIUS)?

 

An Internet standard protocol called Remote Authentication Dial In User Service (RADIUS) offers centralized authentication, accounting, and IP management services for users of remote access in a dispersed dial-up network.

 

A Network Access Server (NAS) functions as a client to a RADIUS server in the RADIUS client-server architecture. Using the RADIUS standard protocol specified in RFC 2865, the system, serving as the NAS, delivers user and connection information to a selected RADIUS server.

 

RADIUS servers respond to user connection requests by authenticating the user and then returning to the NAS (the system) any configuration data required for the NAS to provide permitted services to the authenticated dial-in user.

 

The system can direct authentication requests to a different server in the event that a RADIUS server cannot be contacted. Due to this, multinational corporations may provide their users with dial-in access with a special login user ID for corporate-wide access, regardless of the access point being used.

 

Also Read | What is Network Access Control?

 

How does RADIUS work?

 

The RADIUS server validates the authentication request after receiving it, and then it decrypts the data packet to gain access to the user name and password data. The relevant security system that is supported receives the information. This might be a commercial security system, a custom-built security system, Kerberos, UNIX password files, or even a commercial security system.

 

Any services that the authenticated user is permitted to access, such as an IP address, are sent back to the system by the RADIUS server. Similar procedures are used to handle RADIUS accounting requests. A specified RADIUS accounting server may receive accounting data from remote users. RFC 2866 outlines the RADIUS accounting standard protocol. By recording the data from the RADIUS accounting request, the RADIUS accounting server responds to incoming accounting requests.

 

RADIUS gives a business the ability to keep track of user profiles in a common database that all distant servers can access. Better security is provided by having a central database, which enables a business to set up a policy that can be executed at a single network point that is administered. 

 

A central database also makes it simpler to retain network statistics and track use for the purpose of invoicing the supplier of network access or internet service. Leading networking product businesses to employ RADIUS, a de facto industry standard that was developed in 1991 by former networking vendor Livingston Enterprises. As described in RFC 2865, the RADIUS protocol was approved as a draft standard by the Internet Engineering Task Force in 2000.

 

RADIUS was first created to assist several customers connecting remotely to internet service providers (ISPs) or business networks via modem pools or other point-to-point serial line connections. Nowadays, RADIUS is frequently used for remote user access via a variety of networks, including wireless networks, Ethernet networks, and various forms of remote user access through the internet.

 

The Authentication Process of RADIUS:

 

Remote network users connect to their networks using the RADIUS protocol via a network access server (NAS). To get authentication, authorization, and configuration details about the remote user, the NAS contacts the authentication server.

 

RADIUS clients are the NAS systems used to access a network, as opposed to other client-server applications where a client is frequently a single person. RADIUS servers function as the authentication server.

 

Access servers function as clients of the RADIUS server in the RADIUS protocol. The servers used by distant users to access the network are given centralized authentication services through the RADIUS protocol.

 

There are several kinds of remote user access authentication servers, such as:

 

• Dial-in servers that use modem pools to facilitate access to corporate or ISP networks.

• servers for virtual private networks that take requests from remote users to establish safe connections to a private network.

• Access points for wireless networks that approve requests for network connections from wireless clients.

• switches for managed network access that employ the 802.1x authenticated access protocol to mediate distant users' access to networks.

 

When authenticating with a distant network, end users only indirectly communicate with the RADIUS server via a network access server. The NAS starts a RADIUS exchange with the authentication server when an end user establishes a connection with a distant network.

 

The request can contain the remote user ID, password, and IP address when a remote user starts a connection over a NAS. The RADIUS server then receives an authentication request from the NAS.

 

RADIUS Protocol:

 

RADIUS is a client/server protocol that stores dial-up customers' profile data in one place on a RADIUS server, which is running certain RADIUS software. In other words, the protocol will check to see whether a client is authentic, find out what kinds of access that client has, and then watch that client while it is connected to the network. The Remote Authentication Dial-In User Service protocol operating on a user's machine will typically be completely out of their control, and the server operators' control over theirs will be minimal. When utilized, the entire procedure is automated.

 

The RADIUS protocol is frequently used on sizable systems with non-trusting users or for transferring across non-trusting user networks. To enable communication through networking, two computers create trust with one another. 

 

When two computers have mutual trust, they may communicate back and forth without incurring much extra expense. Every step of the communication uses a number of authentication and verification phases when the recipient is untrusting.

 

On the Internet more than anywhere else, non-trusting systems and people are prevalent. The computers inside a workplace, a school, or a household trust one another and communicate with ease. 

 

Multiple computers may need to log into the same system simultaneously while using the Internet. These computers could have faith in the machine they are logged into, but they have no such faith in one another. When a local system downloads email or domain information from an ISP server, this situation is quite frequent.

 

There is rarely any trust when information needs to be sent back and forth between two separate ISPs from their respective regions. The Remote Authentication Dial In User Service protocol is used by these big non-trusting systems to keep things running smoothly without having to continually check what the non-trusted system is up to. The technique uses AAA to manage the entire procedure.

 

The network access server (NAS), which permits the client to establish a dial-up connection, is often distinct from the RADIUS server. Any NAS that requires it to authenticate users can access the flat-file ASCII database that an RFC-compliant RADIUS server uses to store all user profile data.

 

Some RADIUS servers can also authenticate users by means of third-party security systems, UNIX password files, Password Authentication Protocol (PAP), Challenge Handshake Authentication Protocol (CHAP), Microsoft Challenge Handshake Authentication Protocol (MS-CHAP), and Network Information Services (NIS).

 

Internet tunneling increases the security of remote access to corporate networks and makes managing distant users easier. Additionally, RADIUS servers are frequently used to give billing statistics.

 

RADIUS authentication methods:

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RADIUS authentication methods

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RADIUS uses two methods for authentication:

 

1. Password Authentication Protocol (PAP): 

 

The user ID and password of the distant user are transmitted by the RADIUS client to the RADIUS authentication server. The server authenticates the user if the credentials are accurate, and the RADIUS client then permits the distant user to access the network.

 

2. Challenge Handshake Authentication Protocol (CHAP): 

 

CHAP authentication sometimes referred to as a three-way handshake, depends on the client and server sharing an encrypted shared secret. Because it can be set up to do several mid-session authentications and encrypts authentication exchanges, CHAP authentication is thought to be more secure than PAP.

 

3. MS-CHAP:

 

This is Microsoft’s version of CHAP. It is used with VPNs.

 

4. Extensible Authentication Protocol (EAP):

 

Wireless networks and point-to-point communications frequently employ the extensible authentication protocol (EAP).

 

It is possible to set up a RADIUS proxy client to send RADIUS authentication requests to other RADIUS servers. Centralized authentication is made possible in big or scattered networks using RADIUS proxies.

 

The directory service software is integrated with the RADIUS protocol, a well-established authentication mechanism that is used in many networking devices for authorization and accounting. For instance, Microsoft's Network Policy Server, which works with Microsoft Active Directory, uses RADIUS.

 

Benefits of RADIUS:

 

Managing user access is greatly facilitated by RADIUS' single platform for user and system authentication. Multiple IT administrators can easily control the same network because of RADIUS' centralized structure.

 

Additionally, the fact that each user in a RADIUS environment has a unique set of credentials does away with the requirement for frequent password changes. By doing this, the weaknesses in traditional password security are reduced.

 

Perhaps most crucially, RADIUS guards against network connections belonging to legitimate users being effectively intercepted by intruders. Every connected user may be confirmed to be who they claim to be and to have the necessary access credentials to perform their duties by network administrators.

 

Challenges of RADIUS:

 

Due to its traditional on-premises implementation, RADIUS can be challenging to set up and maintain and take a lot of time. Implementation and upkeep can be facilitated by cloud-based choices, though.

 

Further complicating the process of installing a new RADIUS server and integrating it into an existing environment are the numerous configuration choices. Efficiencies and production may be hampered by these obstacles.

 

Also, bewildering is the number of RADIUS solutions available. In order to choose the finest RADIUS server, an organization's demands must be assessed, and different solutions must be contrasted. This can be a time-consuming process.

 

Conclusion:

 

When a distant employee wants to access a company's network and data centers, RADIUS is frequently used. It makes sure that only verified, authorized individuals are given access while causing the least amount of disturbance to the worker's productivity.

 

RADIUS is also a crucial component of the zero trust security paradigm, which views all users as potential threats. The authentication and authorization components that reliably confirm a user's identity and rights depend on RADIUS.